Amgen Inc. (AMGN)

Amgen is one of the largest independent biotechs, with a diversified portfolio of fourteen leading products (Prolia/XGEVA, Repatha, Otezla, ENBREL, TEZSPIRE, KYPROLIS) that spreads risk across multiple products—without the extreme single-product concentration other oncology pharmas face. Consolidated growth (+10% in 2025) masks large divergences: Repatha and recent launches (TEZSPIRE, UPLIZNA, IMDELLTRA) grow strongly, while Prolia/XGEVA and ENBREL already face biosimilar erosion and price controls combining federal Medicare with at least two state affordability boards.

A diversified biotech is valued on P/E over normalized net income, which gives the equity value directly. Trailing twelve-month GAAP net income ($7.80bn) still carries a $400M residual of the Otezla intangible impairment ($1.2bn in total during 2025, tied to Medicare price setting) falling inside that window, net of a $264M gain on debt extinguishment from fiscal 2025 (Note 16, Financing Arrangements) — normalized income comes to ~$7.94bn, and at ~$445 the P/E is ~28×.

The base case starts from the guidance the company itself published for 2026 — revenues of $37.1bn to $38.5bn and GAAP earnings per share of $15.62 to $17.10 — rather than from the historical trajectory: +2.1% at the midpoint, with earnings per share of $16.39. From there it recovers toward +6.0% by year 5, and it is worth seeing why: the eroding block (Prolia, XGEVA, ENBREL) is 17% of revenue and falling 33%, while the rest of the portfolio grows 20%, so as the block loses weight the consolidated figure recovers through the arithmetic of the mix, not because the business improves. The normalized net margin expands from ~21.3% to ~25.0% (cost discipline + falling interest expense as debt is repaid + amortization of Horizon-related intangibles declining from $4.3bn in 2025 to $2.2bn in 2030 on a known schedule), at an exit multiple of 16× (the middle of the pharma band). That gives ~$351 per share → -2% per year including the dividend.

No margin of safety: the price already discounts a demanding scenario. Amgen trades near its 52-week high ($391 versus ~$445), far from a cycle trough or forced selling—no clear source of mispricing discount. The verdict is Overvalued: real quality (diversified portfolio, ROIC above the 10% bar, active debt deleveraging) at a price already balancing the pipeline (MariTide, Repatha, TEZSPIRE) against measurable legacy-franchise erosion, plus state price controls now adding to federal controls on ENBREL. Not a bargain, nor obviously overpriced.

Three things to watch. The pace of Prolia/XGEVA biosimilar erosion—if it accelerates beyond modeling, the base case degrades toward the adverse scenario. TAVNEOS outcome: the FDA requested voluntary withdrawal January 16, 2026 (Amgen declined January 28, 2026 and continues evaluating the path with the regulator), with $2.5bn intangible at stake plus annual sales (~$459M in 2025) if adverse. And the IRS litigation over Puerto Rico (2010-2018, with gross exposure up to ~$10.7bn against net equity of $8.66bn at end-2025, and audits of later years already underway)—ruling not expected before H2 2026. Debt repayment (already $6.0bn in 2025) signals discipline to monitor, alongside the pipeline (MariTide, six Phase 3s), which if delivered opens a meaningfully scaled franchise.